Another woman was also killed and more than a dozen others have been injured in a mass shooting in Toronto.

Police responded to reports of an incident in the city's Riverdale neighbourhood around 10pm Sunday night (local time). Toronto police initially advised nine victims had been shot, with the shooter killed.

Later, police chief Mark Saunders updated media that 15 people had been shot, including the shooter. Saunders said one "young lady" was dead, while a nine-year-old girl was in critical condition in hospital.

Saunders said police had engaged in a gunfight with the shooter -- who was armed with a handgun -- and while he did not comment on the possible motivations for the shooting, he did not rule out terrorism.